Driving device for a windshield wiper, especially for vehicle window panes

ABSTRACT

The invention is directed to a drive device for a wiper installation, in particular for windows in motor vehicles, with a holding element which is arranged so as to be stationary and has, at least on one side, a bearing for receiving a wiper shaft, wherein the bearing is produced as a plastic part and is connected in a positive and frictional engagement with the holding element by means of a partial plastic deformation of the holding element. 
     It is provided that the bearing ( 14 ) has a connection piece ( 38 ) engaged by a bushing ( 40 ), wherein the holding element ( 12 ) engages in an annular space ( 58 ) formed between the connection piece ( 38 ) and the bushing ( 40 ), the holding element ( 12 ) is partially plastically deformable inside the annular space ( 58 ), and there is a positive engagement ( 62 ) between the holding element ( 12 ) and the connection piece ( 38 ) and a frictional engagement ( 64 ) between the holding element ( 12 ) and the connection piece ( 38 ) and between the holding element ( 12 ) and the bushing ( 40 ).

BACKGROUND OF THE INVENTION

The invention is directed to a drive device for a wiper installation, inparticular for windows of motor vehicles.

Drive devices of the generic type are known. They have a holdingelement, generally constructed as a hollow rod, which carries, at itsfree ends, bearings for receiving a wiper shaft. The bearings arenormally produced as diecast parts or as plastic injection-molded parts.In order to connect the bearings with the holding element in a positiveand frictional engagement, it is known to construct the bearings with aconnection piece which engages in the holding element constructed as ahollow rod. Subsequently, the holding element which is generally ashaped sheet metal part is acted upon by a joining force which resultsin a plastic deformation of the holding element in some areas. In orderto achieve a frictional and positive engagement, the connection piece ofthe bearing has recesses in the area of the plastic deformation of theholding element, wherein the material of the holding element can beforced into these recesses. It is disadvantageous in the known drivedevices that this frictional and positive engagement between thebearing, which is constructed in particular as a plastic part, and theholding element cannot be produced with sufficient security because, dueto the modulus of elasticity of the plastic, this plastic tends to flowduring the pressing of the joining connection between the bearing andthe holding element.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide anactuating device which avoids the disadvantages of the prior art.

In keeping with these objects, one feature of present invention resides,briefly stated, in a drive device for a wiper installation, in which thebearing has a connection piece engaged by a bushing, the holding elementengages in an annular space between the connection piece and the bushingand is partially plastically deformable inside the annular space, apositive engagement is provided between the holding element and theconnection piece and a frictional engagement is provided between theholding element and the connection piece and between the holding elementand the bushing.

In contrast to the prior art, the drive device according to theinvention offers the advantage that a secure positive and frictionalengagement is produced between the bearing and holding element in asimple manner. As an advantageous result of the fact that the bearinghas a connection piece engaged by a bushing, wherein the holding elementengages in an annular space formed between the connection piece and thebushing, the holding element is plastically deformable inside theannular space, and a positive engagement exists between the holdingelement and the connection piece and a frictional engagement existsbetween the holding element and the connection piece and between theholding element and the bushing, it is achieved that the holding elementis essentially clamped in the annular space between the connection pieceand the holding element of the bearing due to its plastic deformation.Therefore, added axial and/or radial force acting on the joiningconnection can be intercepted via the frictional engagement between thebushing and the holding element, so that the bearing is reliablyfastened to the holding element. In particular, it is possible tocompensate for manufacturing tolerances in a simple manner by theclamping of the holding element between the connection piece and thebushing. Manufacturing tolerances of the bearing, especially itsconnection piece which can be inserted into the holding element, as wellas manufacturing tolerances of the holding element itself, can becompensated by the clamping in the annular space of the bearing betweenthe connection piece and the bushing.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained more fully in the following embodimentexample with reference to the accompanying drawings.

FIG. 1 shows a schematic overview of a drive device for windshieldwipers;

FIGS. 2 and 3 show a top view and a longitudinal section of a bearing;and

FIGS. 4 and 5 show longitudinal sections of a connection point betweenthe bearing and holding element rotated in each instance by 90°.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows an overview of a drive device 10 for windshield wipers inmotor vehicles. The drive device 10 has a holding element 12 which isarranged in a stationary manner in a motor vehicle. The holding element12 has a bearing 14 at both ends. The bearings 14 are joined with theholding element 12 in a fastening area 16 whose specific construction isexplained in more detail with reference to FIGS. 2 to 5. At their sidesremote of the holding element 12, the bearings 14 are provided with afastening element 18 having a receptacle for fastening means. Thestationary fastening of the drive device 10 to a part of the body of themotor vehicle is carried out by means of the fastening elements 18.

The bearings 14 receive a wiper shaft 20 which is arranged so as to berotatable but fixed axially. The wiper shaft 20 projects out over thebearing 14, wherein a coupling rod linkage 22 acts at the wiper shaft20. An arm 24 is connected with the wiper shaft 20 so as to be fixedwith respect to rotation relative to it on the one hand and is connectedwith a coupling rod 28 via a joint 26 on the other hand. A wiper armwhich carries a wiper blade in a known manner can be fastened to thefree end of the wiper shaft 20 so as to be fixed with respect torotation relative to it.

The drive device 10 also has a drive motor 30 which drives a crank 34via a gear unit 32. The crank 34 is connected in an articulated mannerwith the coupling rods 28.

The functioning of the drive device 10 is known in general, so that amore detailed explanation can be omitted within the framework of thepresent description. The crank 34 is set in rotation via the drive motor30. The coupling rods 28 accordingly undergo an axial movement which isoriented essentially along its longitudinal axis. This axial movement istransformed into a swiveling movement via the coupling rods 24 and istransmitted to the wiper shafts 20. The wiper arms which are arranged atthe wiper shafts 20 accordingly undergo the known swiveling movement.

The construction of the bearing 14 according to the invention,particularly of the fastening area 16, will be described hereinafterwith reference to FIGS. 2 to 5. The bearing 14 comprises a plasticmolded part which can be produced as a plastic injection-molded part byknown methods in a manner suitable for series production.

The bearing 14 is shown in FIG. 2 in a top view and is shown in FIG. 3in longitudinal section corresponding to line A-B according to FIG. 2.Parts identical to those in FIG. 1 are provided with the same referencenumbers and are not described again. The bearing 14 forms a receptacle36 for the wiper shaft 20. This receptacle 36 has a through-opening 38in which the wiper shaft 20 can be arranged so as to be rotatable but sothat it can be fixed axially. A connection piece 38, around which abushing 40 engages, extends in the direction of the holding element 12(FIG. 1). Both the connection piece 38 and the bushing 40 areconstructed in one piece with the other areas and shaped portions of thebearing 14. The bushing 40 has diametrically opposed openings 42 whoseaxial extension is selected in such a way that pockets 44 introduced inthe connection piece 38 lie in the area of the openings 42. The pockets44 are constructed as depressions 48 arranged radially relative to alongitudinal axis 46 of the bearing 14.

The connection piece 38 passes into a portion 52 of smaller diameter viaa conically tapering outer surface 50. A depression 54 is formed in thebushing 40 in the area of the outer surface 50 either as an opening orso as to be bridged by an internal web or crosspiece 56 which serves asa predetermined breaking point in a manner to be explained hereinafter.

It is clear, especially from the sectional view in FIG. 3, that thearrangement of the connection piece 38 and bushing 40 results in anannular space 58 between the connection piece 38 and the bushing 40.

The annular space 58 between the connection piece 38 and the bushing 40is formed in such a way that a portion 61 of the annular space 58located in the vicinity of the base 59 corresponds to a materialthickness of the holding element 12, so that this holding element 12, inpreparation for the joining connection described more fully withreference to FIGS. 4 and 5, can be introduced into the annular space 58so as to clamp to some extent and is accordingly pre-arranged inposition.

FIG. 5 is a sectional view corresponding to FIG. 3 which shows thefastening area 16 between the bearing 14 and holding element 12. Theholding element 12 is constructed as a hollow profile, especially as ahollow cylinder, and is guided in the annular space 58 by its end 60.Accordingly, the holding element 12 engages around the connection piece38 on the one hand and, on the other hand, is itself grasped by thebushing 40. In this position, the holding element 12 is acted upon by ajoining force F. For this purpose, dies of a joining device, not shown,reach through the openings 42 and the depression 54. The geometry of thedies is adapted to the cross-sectional surface of the pockets 44 or tothe contour of the outer surface 50 taking into account a materialthickness of the holding element 12. Due to the application of thejoining force F to the holding element 12, a positive engagement 62 anda frictional engagement 64 are formed. The holding element 12 isplastically deformed, so that portions 66 of the holding element 12 areforced into the pockets 44. Due to the positive engagement 62, thebearing 14 is connected with the holding element 12 in such a way thatforces acting axial to the longitudinal axis 46 cannot lead to adisengagement of the joining connection between the bearing 14 and theholding element 12. At the same time, the bearing 14 is secured againstrotation because the positive engagement 62 acts on the pockets 44 thatare formed radially opposite one another. In the areas of the holdingelement 12 which are rotated by 90° in the view in FIG. 5, the end 60 ofthe holding element 12 contacts the connection piece 38 essentiallyparallel as is shown in the view in FIG. 4 which is rotated by 90° withrespect to FIG. 5.

In the area of the outer surface 50 which, as is shown in the view inFIG. 4, is likewise formed only at diametrically opposite sides of theconnection piece 38, the application of joining force F in this arealeads to the deflection of portions 68 of the holding element 12 whichextend so as to be rotated essentially by 90° relative thereto.Accordingly, the plastic deformation of the holding element 12 in thedirection of the outer surfaces 50 leads, in addition, to a radialoutward shaping in portions 68 of the holding element 12. In so doing,the portions 68 come into contact with the bushing 40 and form anadditional frictional engagement 64.

Accordingly, as a whole, due to the construction of the bearing 14,especially in that a connection piece 38 is provided, which is engagedby the bushing 40, for forming a positive engagement between the holdingelement 12 and the connection piece 38 and for forming a frictionalengagement between the holding element 12 and the connection piece 38and, at the same time, between the holding element 12 and the bushing40, a reliable, lasting joining connection is realized between theholding element 12 and the bearing 14 which safely withstands mechanicalloading that occurs during prescribed use of the drive device 10, forexample, due to vibrations, and does not become loose. This ensures anexact guidance of the wiper shaft 20 engaging through the bearings 14,so that the latter continues to run smoothly.

Besides the additional frictional engagement 64 between the holdingelement 12 and the bushing 40, the formation of the annular space 58also makes it possible to compensate for manufacturing tolerances of thebearing 14, especially its connection piece 38, and of the holdingelement 12.

According to further embodiment examples, not shown, there is no needfor separate construction of depressions 54, for example. For thispurpose, the openings 42 are lengthened axially in a correspondingmanner so that the plastic deformation of the holding element 12 throughthe openings 42 can be effected at the outer surfaces 50 of theconnection piece 38. According to another variant, the joining force Fcan be exerted directly on the bushing 40 in the area of the outersurface 50 of the connection piece 38, so that the bushing 40 deformselastically and the joining force F is applied to the holding element 12by way of the bushing 40. At the conclusion of the joining process, thebushing 40 returns to its original position because of its elasticity.

What is claimed is:
 1. A drive device for a wiper installation forwindows in motor vehicles, the drive device comprising a holding elementarranged so as to be stationary; a bearing provided at least on one sideof said holding element for receiving a wiper shaft, said bearing beingformed as a plastic part and connected in a positive and frictionalengagement with said holding element by a partial plastic deformation ofsaid holding element, said bearing having a connection piece engaged bya bushing so that an annular space is formed between said connectionpiece and said bushing, and both said connection piece and said bushingbeing of one piece with other areas of said bearing, said holdingelement engaging in said annular space between said connection piece andsaid bushing and being plastically deformable inside said annular space,said holding element and said connection piece being in a positiveengagement with one another, said holding element and said connectionpiece being in a frictional engagement with one another, and saidholding element and said bushing being in a frictional engagement withone another.
 2. A drive device for a wiper installation for windows inmotor vehicles, the drive device comprising a holding element arrangedso as to be stationary; a bearing provided at least on one side of saidholding element for receiving a wiper shaft, said bearing being formedas a plastic part and connected in a positive and frictional engagementwith said holding element by a partial plastic deformation of saidholding element, said bearing having a connection piece engaged by abushing so that an annular space is formed between said connection pieceand said bushing, said holding element engaging in said annular spacebetween said connection piece and said bushing and being plasticallydeformable inside said annular space, said holding element and saidconnection piece being in a positive engagement with one another, saidholding element and said connection piece being in a frictionalengagement with one another, and said holding element and said bushingbeing in a frictional engagement with one another, said bushing havingat least one opening to which are allocated pockets formed in saidconnection piece, said holding element being actable upon through saidopening by adjoining force, so that said holding element can be forcedpartially into said pockets.
 3. A drive device as defined in claim 2,wherein said bushing has, in a diametrically opposite arrangement twoopenings and corresponding pockets.
 4. A drive device for a wiperinstallation for windows in motor vehicles, the drive device comprisinga holding element arranged so as to be stationary; a bearing provided atleast on one side of said holding element for receiving a wiper shaft,said bearing being formed as a plastic part and connected in a positiveand frictional engagement with said holding element by a partial plasticdeformation of said holding element, said bearing having a connectionpiece engaged by a bushing so that an annular space is formed betweensaid connection piece and said bushing, said holding element engaging insaid annular space between said connection piece and said bushing andbeing plastically deformable inside said annular space, said holdingelement and said connection piece being in a positive engagement withone another, said holding element and said connection piece being in africtional engagement with one another, and said holding element andsaid bushing being in a frictional engagement with one another, said,connection piece having a conically tapering outer surface.
 5. A drivedevice for a wiper installation for windows in motor vehicles, the drivedevice comprising a holding element arranged so as to be stationary; abearing provided at least on one side of said holding element forreceiving a wiper shaft, said bearing being formed as a plastic part andconnected in a positive and frictional engagement with said holdingelement by a partial plastic deformation of said holding element, saidbearing having a connection piece engaged by a bushing so that anannular space is formed between said connection piece and said bushing,said holding element engaging in said annular space between saidconnection piece and said bushing and being plastically deformableinside said annular space, said holding element and said connectionpiece being in a positive engagement with one another, said holdingelement and said connection piece being in a frictional engagement withone another, and said holding element and said bushing being in africtional engagement with one another, said bushing having apre-stamped depression in an area of an outer surface.
 6. A drive deviceas defined in claim 5, wherein said outer surface is formed atdiametrically opposite portions of said connection piece.
 7. A drivedevice for a wiper installation for windows in motor vehicles, the drivedevice comprising a holding element arranged so as to be stationary; abearing provided at least on one side of said holding element forreceiving a wiper shaft, said bearing being formed as a plastic part andconnected in a positive and frictional engagement with said holdingelement by a partial plastic deformation of said holding element, saidbearing having a connection piece engaged by a bushing so that anannular space is formed between said connection piece and said bushing,said holding element engaging in said annular space between saidconnection piece and said bushing and being plastically deformableinside said annular space, said holding element and said connectionpiece being in a positive engagement with one another, said holdingelement and said connection piece being in a frictional engagement withone another, and said holding element and said bushing being in africtional engagement with one another, said holding element having anouter surface formed so that an adjoining force can be applied to saidholding element in an area of said outer surface, so that a plasticradially inwardly directed deformation of said holding element iseffected and portions of said holding element extending at a roughly 900rotation to said outer surface are deformed radially outwards, so thatsaid portions come into contact with said bushing to form saidfrictional engagement.